Final answer:
In ecosystems, the production of organic material by producers can be limited by factors such as limited sunlight and lack of nutrients, along with other limiting factors like water availability and temperature.
Step-by-step explanation:
The question addresses the factors that limit the production of organic material by producers in ecosystems. Among the options provided, both limited sunlight (A) and lack of nutrients (C) are factors that can limit the ability of producers to synthesize organic material. Limited sunlight affects the process of photosynthesis which is essential for energy production in plants, while a lack of nutrients constrains plant growth and biomass accumulation. It is also important to consider other limiting factors such as water availability, oxygen levels, temperature, space, and predation, which can all influence ecosystem productivity.
Abundance of consumers (B), overpopulation of predators (D), and events like fire or disease can all have secondary effects by altering the balance of organisms within an ecosystem, but are not directly limiting the production of organic material by producers.